Danish authorities had been searching for Kim Wall since she failed to return from an interview with Peter Madsen.
Photograph: Tom Wall/AFP/Getty Images

Police in Denmark have identified a headless torso found in the Copenhagen waterside as that of Swedish journalist Kim Wall, who police believe was killed on board a Danish inventor’s homemade submarine.

Speaking at a press conference on Wednesday morning, Copenhagen police’s vice-president, Jens Møller, said metal weights had been attached to the body to prevent it from floating to the surface.

“The body bears the mark of having, most likely, been inflicted deliberate damage with the purpose of ensuring that gasses can pass out of the body – possibly in an attempt to avoid that a body rises from the seabed,” Møller said.

He also said DNA taken from a hairbrush and toothbrush belonging to 30-year-old Wall had matched that of blood found on the submarine.

Peter Madsen, a Danish inventor about whom Wall is believed to have been writing a feature article, was charged with manslaughter last week. He told a court hearing this week that Wall died in an accident on his vessel and that he “buried” her at sea.

This marked a change from a previous statement in which he claimed to have dropped off Wall alive on the tip of an island off Copenhagen late on 10 August before the vessel sank. Madsen denies manslaughter.

Wall’s mother, Ingrid, posted on Facebook on Wednesday: “We cannot see the end of the disaster yet, and a lot of questions are still to be answered.

“The tragedy has hit not only us and other families, but friends and colleagues all over the world. During the horrendous days since Kim disappeared, we have received countless evidence of how loved and appreciated she has been, as a human and friend as well as a professional journalist. From all corners of the world comes evidence of Kim’s ability to be a person who makes a difference.”

Originally from Sweden, Wall had degrees from Columbia University and the London School of Economics, and had written for publications including the New York Times, Foreign Policy, Time and the Guardian.

Danish authorities had been searching for the reporter since she failed to return from an interview with Madsen on board the Nautilus. She was last seen on the vessel by several people in waters off Copenhagen on the evening of 10 August. Her boyfriend reported her missing in the early hours the next day.

The submarine was later also reported missing, and rescue crews located it shortly after 10am on 11 August in Køge Bay, south of the Danish capital. At about 11am, Madsen jumped into the water after the submarine started to sink. He told personnel on the boat that rescued him that there had been a problem with the ballast tank and something had gone wrong when he tried to repair it.

Police refloated the Nautilus and towed it into harbour for investigation, later suggesting that Madsen may have sunk the boat on purpose to hide evidence.

Madsen appeared before a judge on 12 August for preliminary questioning. The case is not open to the public to protect further investigations, police said.

On Wednesday Madsen’s lawyer said her client still maintains that Wall died accidentally, and that the discovery of the journalist’s torso did not mean he was guilty of killing her.

“It doesn’t change my client’s explanation that an accident happened,” Betina Hald Engmark told Danish tabloid BT. “No matter what, we find it very positive that she has been found now.”

An entrepreneur, artist, submarine builder and aerospace engineer, Madsen, 46, nicknamed Rocket, has enjoyed a cult status in his native Denmark. For years, a team built around him and the aerospace engineer Kristian von Bengtson have worked on designing a rocket-driven spacecraft.

The Nautilus, which was Madsen’s third design for a “midget submarine” vessel and became the largest privately built submarine when it was unveiled in 2008, has been his most spectacular invention to date.

Measuring almost 18 metres and weighing 40 tonnes, it can be operated by one person from its control room. Madsen was known to regularly take fans and submarine enthusiasts on tours through the Øresund strait. Able to submerge in approximately 20 seconds, the boat can carry up to eight people to 100 metres below sea level.

On Tuesday a support group set up in his honour distanced itself from the inventor. “The dream is burst. In view of the latest information released by the Copenhagen police today, there is regrettably no way for us to continue as part of the Raket-Madsen Support Group,” the group’s president announced on its website.

Danish police said that in light of the findings they would look afresh into unsolved cases such as the murder of a Japanese tourist in 1986. Body parts of 22-year-old Kazuko Toyonaga were found in plastic bags at separate locations in the waters outside Copenhagen almost a month after the student disappeared on her travels through Scandinavia.

“It would be sad to let this tragedy define what Kim’s life was,” Reed said. “She should be remembered for her insatiable curiosity, and her drive to find stories which no other journalist had touched before.

“She was deeply interested in the lives of outliers, people who lived their lives in their own terms. Her passion for her subjects was infectious, and as such she was an absolute pleasure to work with. She was a true professional.”